This invention relates to a hydrogenated polymer which is excellent in mechanical strength, heat resistance, weatherability, and processability and provides compositions having high impact resistance and excellent moldability when blended with other thermoplastic resins or rubbery polymers. The invention also relates to a composition containing the polymer and a film or a sheet containing the polymer.
Having unsaturated double bonds, a conjugated diene polymer is inferior in heat stability, weatherability, and ozone resistance. Methods for improving these properties by hydrogenating the unsaturated double bonds have long been known. Such methods are disclosed, e.g., in JP-A-56-30447 and JP-A-2-36244.
On the other hand, a hydrogenated block copolymer comprising a conjugated diene and a vinyl aromatic hydrocarbon possesses elasticity at ambient temperature without vulcanization like vulcanized natural rubber and synthetic rubber and exhibits the same processability in high temperature as thermoplastic resins and has therefore been widely used in the fields of plastic modification, pressure-sensitive adhesives, automobile parts, medical equipment, and the like. In order to draw similar characteristics from a polymer consisting of a conjugated diene compound, it has recently been attempted to hydrogenate a conjugated diene polymer having a vinyl bond-rich block and a vinyl bond-poor block in the polymer chain.
For instance, JP-A-56-30455 discloses a composition comprising (1) a hydrogenated diblock copolymer consisting of a first block having not more than 15% by weight 1,2-microstructure and a second block having at least 30% by weight 1,2-microstructure and (2) an xcex1-olefin polymer. JP-A-3-128957 proposes a thermoplastic elastomer composition comprising (1) a hydrogenated diene polymer obtained by hydrogenating a block copolymer consisting of polybutadiene block segments having a 1,2-vinyl bond content of not more than 20% by weight and block segments of which the butadiene unit portion has a 1,2-vinyl bond content of 25 to 95% by weight in the butadiene and (2) a thermoplastic resin and/or a rubbery polymer. JP-A-10-25395 teaches a hydrogenated block copolymer composition obtained by hydrogenating block copolymers comprising conjugated diene polymer blocks having a vinyl bond content less than 90% by weight and a difference of 10% by weight or more between maximum and minimum vinyl bond contents in the conjugated diene polymer.
These block copolymers have poor mechanical strength however. Hydrogenated conjugated diene polymers having further improved mechanical strength have been desired for individual use or a combined use with various thermoplastic resins or rubbery substances.
An object of the present invention is to provide a hydrogenated polymer excellent in mechanical strength, heat resistance, weatherability, and processability and fit for industrial production. Another object of the invention is to provide a composition of the hydrogenated polymer and other thermoplastic resins or rubbery polymers which is excellent in impact resistance and moldability. A still other object of the invention is to provide a film or a sheet containing the hydrogenated polymer which is excellent in impact resistance and transparency.
The present inventors have conducted extensive investigations to settle the above-described problems and found, as a result, that the above objects can be achieved by a certain hydrogenated polymer which is a hydrogenation product of a conjugated diene polymer having a specific vinyl bond content, in which the crystallizing peak temperature and the hydrogenated vinyl bond content are in a specific relationship, and of which the molecular weight and the molecular weight distribution are in specific ranges. The present invention has been completed based on this finding.
The present invention provides a hydrogenated polymer obtained by hydrogenating a conjugated diene polymer having an average vinyl bond content of 20% by weight or more and less than 40% by weight to a degree such that 85% or more of double bond residues in the conjugated diene unit portion are hydrogenated, wherein
(1) the crystallizing peak temperature and the hydrogenated vinyl bond content satisfy the formula:
xe2x88x922.8V+100 less than T less than xe2x88x922.8V+130
wherein T is the crystallizing peak temperature (xc2x0 C.) measured by DSC; and V is the hydrogenated vinyl bond content (%),
(2) the molecular weight is 60,000 to 600,000, and
(3) the molecular weight distribution is 1.55 to 5.0.
The present invention also provides a composition comprising the hydrogenated polymer and a thermoplastic resin and/or a rubbery polymer. The present invention also provides a film or a sheet containing the hydrogenated polymer.